The reasons for the decrease in the number of teen births are unknown, but government officials are reassured by the data.

"Compared to infants born to older mothers, infants born to adolescent mothers are at a higher risk for low birth weight, either from being born prematurely or from failure to grow appropriately in the womb," Dr. Alan E. Guttmacher, director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, said in a briefing. (The institute is a branch of NIH.) "Children of adolescent mothers are less likely to earn high school diplomas than are children of older mothers. Adolescents who give birth are less likely to earn high school diplomas themselves and their reduced educational attainment limits employment prospects and future earnings."

However, Dr. Steven Lipshultz, professor and chair of pediatrics at the University of Miami's Miller School of Medicine, says the data on teen births are incomplete, because they don't take into account how many teenagers miscarried or had abortions. The number of teenage girls getting pregnant may not be decreasing.

The report, compiled by the Federal Interagency Forum on Child and Family Statistics, uses the most current data on children ages 0 to 17 to provide a snapshot of children's health and behavior as well as their social, family, educational, physical and economic environments.

Some adolescent health experts say the declines in binge drinking by 12th graders and teen birth rates are very positive and reflect the effectiveness of efforts to raise awareness about issues that affect teenagers.

"I think increased awareness and education have had an impact," said Alan Hilfer, chief psychologist at Maimonides Medical Center in Brooklyn, N.Y. "They've also increased the awareness of parents, and parents may be working harder at monitoring their kids and helping kids make better decisions."

The declines are small. Teen birth rates decreased from 21.7 per 1,000 to 20.1 per 1,000 over a two-year period and drinking among 12th graders decreased from 25 percent to 23 percent over a two-year period. But, says Hilfer, "any drop is good news."

Lipshultz adds that while the decline in binge drinking is positive, it still means that about a quarter of 12th graders are engaging in this risky behavior.

"It's going in the right direction, but it's still a significant issue and its magnitude is still large," he said.

The data, he also said, may not be an accurate reflection of how big the problem is, since teens may not honestly report their drinking habits.

The statistic showing that more eighth graders are trying illegal drugs is something Hilfer called "unsettling," and he said that the age of experimentation seems to get younger and younger over time.

The debate over the legalization of marijuana as well as more access to the drug may both be contributing factors, he said.

But because a significant amount of teenagers are still having babies, drinking and using drugs, Lipshultz wonders whether educational efforts are really working.

"If nearly one-fourth of 12th graders have been binge drinking, I'm not sure we can say our interventions are making a difference," he said.

Despite his skepticism about some of the trends, Lipshultz said the report still offers tremendous value.

"Although these results are not earth-shattering changes, this report is really important, because it can guide policies that affect children's health."